This circuit was found in a Popular Electronics from the 90s. It is based on components still common today and an optical coupler for the triac. The sensor is a thermistor.
This circuit takes advantage of the noise generated at the junction of a zener diode of any type....
This low-frequency oscillator was found in a 1963 documentation. Capacitors determine frequency. The...
This configuration with FET and Unijunction can be found elsewhere on this site. The JFET admits...